GPS, as well as other tools like Motionize can be great training tools to build upon.
It's usually best to obtain proper paddling training from the beginning - so that you do not develop bad habits that take longer to fix later.
If you are not able to get proper training from a coach or instructor, take the next best thing:
Have a friend take a video of your paddling from different angles.
This will allow you to criticize your paddling in the comfort of your home - as long as you have some knowledge of what you are looking for…
Without video feedback, I assure you that your body will lie to you… it's the same thing in skiing, rock climbing, snowboarding, swimming, etc… My students were always blown away after seeing a video of themselves. Heck, video is so important that it's even worth paying someone to film you for couple of hours of their time.
After that… I can see where Motionize would come in - even though, again, I am trying to be a minimalist.